Monoclonal Antibodies Recognize a Novel Cell Death Receptor and a Decoy Receptor on Granulosa Cells of Porcine Ovarian Follicles.

Abstract

We prepared IgM and IgG (PFG-5 and PFG-6, respectively) monoclonal antibodies against granulosa cells prepared from healthy antral follicles of porcine ovaries. PFG-5 antibody specifically recognized two cell-membrane proteins (PFG-5 antigen: 55 kD, pl 5.9, and PFG-6 antigen: 42 kD, pl 5.2), and PFG-6 antibody recognized PFG-6 antigen. Immunochemical reactions of these antibodies were only detected in follicular granulosa cells but not any other ovarian tissues for organs. Both antigens were detected in granulose cells of healthy follicles, but PFG-6 antigen disappeard in granulosa cells of atretic follicles. When the isolated granulosa cells prepared from healthy follicles were cultured in medium containing PFG-5 antibody, the cells underwent apoptosis, and co-incubation with PFG-6 antibody inhibited PFG-5 antibody inducible apoptosis. These observations suggested that PFG-5 antigen is a novel cell death receptor, which is different from well-known apoptosis-mediating receptors (Fas or tumor necrosis factor receptor), and that PFG-6 antigen may act as a decoy receptor and inhibit apoptotic signals through PFG-5 antigen.